The problem of leaf disposal has changed over the past several decades. Previously, leaves and other organic lawn and garden debris such as tree limbs and branches were raked by hand, collected and burned in an open pile. As concerns over clear air increased, open burning of lawn and garden debris was banned.
Leaf, garden and lawn debris was then collected in piles and allowed to decompose or was hauled or taken to landfills for burying. Decomposition of intact leaves is slow and may take several years before the material has completely decayed. For the last few decades, the burial of leaves and lawn debris has been an effective disposal method. In recent years as environmental concerns about landfills has increased, the cost of burying trash, garbage, and debris has escalated. The availability of landfills has become limited. Landfill disposal rates have been increasing. In some areas, local disposal costs have increased from $3 to $5 a load to $28 to $35 a load.
Many devices have been created to deal with the problem of leaf, garden and lawn debris. Several are vacuum and pulverizing devices such as U.S. Pat. Nos. 2,658,318, 3,049,857, 3,668,479 and 3,712,353. Others are only vacuums such as U.S. Pat. No. 4,325,163 or are only wood or limb chippers U.S. Pat. No. 3,384,311. None of these prior art devices have vacuumed up the leaf, garden and lawn debris, shredded the leaves and also chipped the lawn debris such as limbs and branches.
U.S. Pat. No. 4,360,166 to Biersack discloses a motor-driven shredding apparatus with an inlet provided for lightweight garden waste and a second inlet for twigs, branches and the like. The inlet provided for lightweight garden waste has an essentially vertical orientation and utilizes natural gravitational forces to move the debris shredded by shredding blades through the device wherein it is expelled by stamped lugs. A plurality of counter plates are vertically oriented on the inner surface of the chute to prevent the lightweight debris from being rotated around the chute so that it can be shredded by the shredding blades. The shredding blades are positioned essentially parallel to the hypotenuse of the triangular counter plates and shredding occurs between these surfaces. The trailing edge of the counter plates is positioned generally below the cutting area of the shredding blades. No cooperation between shredding blades and counter plates is present to pull or effect movement toward the subsequent counter plate.
The second inlet receives small twigs or branches for chipping as illustrated in FIG. 5. In column 5 beginning at line 1, Biersack teaches that his invention is designed only to chip pieces of thick branch material. The counter plates as shown in FIG. 6 cooperate with the cutter plate merely to chip the material. Therefore, it is clear that the counter plates were provided as stationary cutting surfaces and do not aid in pulling the material through the device.